Visualizing Tsumego

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walleye
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Re: Visualizing Tsumego

Post by walleye »

Cassandra wrote:
walleye wrote:When I look at it now, the solution is so obvious and so simple, I can't believe I couldn't see it when I first came across it.

The solution isn't that simple.


Oh, but it is. A simple tesuji. If you know the technique, you will see the solution right away. But if you don't, you'll be wandering past it again and again and will never stop to look at it.
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Cassandra
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Re: Visualizing Tsumego

Post by Cassandra »

walleye wrote:Oh, but it is. A simple tesuji. If you know the technique, you will see the solution right away. But if you don't, you'll be wandering past it again and again and will never stop to look at it.

After you have seen the solution, it seems simple.

In the following, I will give some thoughts on the way to the solution and some remarks to topics, which might be overlooked.

Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ . . . . . C C C . . . . |
$$ . . . O . C C Y Y O O . |
$$ . . O . Y Y Y O O X X . |
$$ O . O Y . . . O X O . . |
$$ . . X O O . O O X . O . |
$$ . O . X O X O X . X . . |
$$ . . X X O O X X . . . . |
$$ . . . . X X . . . . . . |
$$ . . . . . . . . . . . . |[/go]

Black's marked stones at the top cannot live on their own.
Eye-space is too small and maximum eye-space would consist of a dead Nakade-shape.

Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ . . . . . . . . . . . . |
$$ . . . Q . . . X X Q Q . |
$$ . . Q . X X X O O X X . |
$$ Q . Q X . . . O # O . . |
$$ . . X O O . O O # . O . |
$$ . O . # O X O # . # . . |
$$ . . # # O O # # . . . . |
$$ . . . . # # . . . . . . |
$$ . . . . . . . . . . . . |[/go]

Black cannot kill any of White's group at the top, so he will have to connect to his stones below.

Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ . . . . . . . . . . . . |
$$ . . . O . . . X X O O . |
$$ . . O . X X X O O X X . |
$$ O . O X . . . O X O . . |
$$ . . X P P . O O X . O . |
$$ . O . X P X O X . X . . |
$$ . . X X P P X X . . . . |
$$ . . . . X X . . . . . . |
$$ . . . . . . . . . . . . |[/go]

To connect, he has to take either White's left-hand group ...

Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ . . . . . . . . . . . . |
$$ . . . O . . . X X O O . |
$$ . . O . X X X P P X X . |
$$ O . O X . . . P X O . . |
$$ . . X O O . P P X . O . |
$$ . O . X O X P X . X . . |
$$ . . X X O O X X . . . . |
$$ . . . . X X . . . . . . |
$$ . . . . . . . . . . . . |[/go]

... or White's right-hand group off the board.

What may be overlooked:
It is not necessary to take both of White's groups off the board !
These two groups seem to be connected, but actually they are NOT.

Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ . . . . . . . . . . . . |
$$ . . . O . . . X X O O . |
$$ . . O . X X X O O Y Y . |
$$ O . O X . . . O X O . . |
$$ . . Y O O . O O X . O . |
$$ . O . X O X O X . X . . |
$$ . . X X O O X X . . . . |
$$ . . . . X X . . . . . . |
$$ . . . . . . . . . . . . |[/go]

What makes it difficult for Black: Both of his groups on the right and on the left have only two liberties.
But:

Click Here To Show Diagram Code
[go]$$W
$$ -----------------------
$$ . . . . . . . . . . . . |
$$ . . . O . . . X X O O . |
$$ . . O . X X X O O X X . |
$$ O . O X . . . O X O . . |
$$ . 3 X O O . O O X . O . |
$$ . O 1 X O X O X . X . . |
$$ . . X X O O X X . . . . |
$$ . . . . X X . . . . . . |
$$ . . . . . . . . . . . . |[/go]

Click Here To Show Diagram Code
[go]$$W
$$ -----------------------
$$ . . . . . . . . . . . . |
$$ . . . O . . . X X O O . |
$$ . . O . X X X O O X X . |
$$ O . O X . . . O X O . . |
$$ . O 5 O O . O O X . O . |
$$ . O O X O X O X . X . . |
$$ . . X X O O X X . . . . |
$$ . . . . X X . . . . . . |
$$ . . . . . . . . . . . . |[/go]

What may be overlooked:
In will take White three moves to connect one of her encircled groups securely to the open.

Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ . . . . . . . . . . . . |
$$ . . . O . . . X X O O . |
$$ . . O . X X X O O Y Y . |
$$ O . O X . . . O X O . . |
$$ . . Y O O . O O X . O . |
$$ . O . X O X O X . X . . |
$$ . . X X O O X X . . . . |
$$ . . . . X X . . . . . . |
$$ . . . . . . . . . . . . |[/go]

What may be overlooked:
Black's group on the right and the left are indeed separated. But they have to be though about as somewhat connected, because they have to do with White's encircled stones.

Click Here To Show Diagram Code
[go]$$W
$$ -----------------------
$$ . . . . . . . . . . . . |
$$ . . . O . . . X X O O . |
$$ . . O . X X X O O X X . |
$$ O . O X . . . O X O . . |
$$ . . X O O 1 O O X . O . |
$$ . O . X O X O X . X . . |
$$ . . X X O O X X . . . . |
$$ . . . . X X . . . . . . |
$$ . . . . . . . . . . . . |[/go]

If it would be White's turn:
Simplest measure for White is to capture the single Black stone. Now she has only one group with four liberties.
One White group means that from here on only one Black group is of really interest. Black has two liberties only and no chance left.
What may be overlooked:
If you have no idea where to start as Black, change to White's point of view and ask yourself where the best point for White could be.

Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ . . . . . . . . . . . . |
$$ . . . O . . . X X O O . |
$$ . . O . X X X O O X X . |
$$ O . O X . 2 . O X O . . |
$$ . . X O O 1 O O X . O . |
$$ . O . X O X O X . X . . |
$$ . . X X O O X X . . . . |
$$ . . . . X X . . . . . . |
$$ . . . . . . . . . . . . |[/go]

Black must prevent White to take the point 1, which is one central point of a symmetrical position, too.
It follows that Black has to start with 1 himself. This move is Double-Atari, so White has to capture with 2.

Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ . . . . . . . . . . . . |
$$ . . . O . . . X X O O . |
$$ . . O . X X X O O X X . |
$$ O . O X . O . O X O . . |
$$ . . X O O . O O X . O . |
$$ . O . X O . O X . X . . |
$$ . . X X O O X X . . . . |
$$ . . . . X X . . . . . . |
$$ . . . . . . . . . . . . |[/go]

I have written before that Ishi-no-shita is difficult to see. So here is the position after White 2.
What may be overlooked:
Now you can see that all of White's encircled groups have three liberties. Three is the number of moves White needs to connect one of her two larger groups to the outside !
This may become a problem, because White has to save both of her two groups to become successful.

Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ . . . . . . . . . . . . |
$$ . . . O . . . X X O O . |
$$ . . O . X X X O O X X . |
$$ O . O X 3 O 5 O X O . . |
$$ . . X O O a O O X . O . |
$$ . O 4 X O . O X . X . . |
$$ . . X X O O X X . . . . |
$$ . . . . X X . . . . . . |
$$ . . . . . . . . . . . . |[/go]

Black continues with 3. White cannot play at a, because this would mean taking an own liberty. After Black gives Atari with 5, the position is symmetrical again.

Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ . . . . . . . . . . . . |
$$ . . . O . . . X X O O . |
$$ . . O . X X X O O X X . |
$$ O . O X X O X O X O . . |
$$ . 6 X O O 7 O O X . O . |
$$ . O O X O . O X . X . . |
$$ . . X X O O X X . . . . |
$$ . . . . X X . . . . . . |
$$ . . . . . . . . . . . . |[/go]

If White captures on the left, Black captures in the centre.

Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ . . . . . . . . . . . . |
$$ . . . O . . . X X O O . |
$$ . . O . X X X O O X X . |
$$ O . O X X . X O X O . . |
$$ . O b O O X O O X . O . |
$$ . O O X O a O X . X . . |
$$ . . X X O O X X . . . . |
$$ . . . . X X . . . . . . |
$$ . . . . . . . . . . . . |[/go]

Due to the hole at b, White cannot connect her stones in Atari with a.

Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ . . . . . . . . . . . . |
$$ . . . O . . . X X O O . |
$$ . . O . X X X O O X X 6 |
$$ O . O X X O X O X O . . |
$$ . . X O O 7 O O X . O . |
$$ . O O X O . O X . X . . |
$$ . . X X O O X X . . . . |
$$ . . . . X X . . . . . . |
$$ . . . . . . . . . . . . |[/go]

If White plays symmetrical on the right, Black's capture with 7 results in Double-Atari.
The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)
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walleye
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Re: Visualizing Tsumego

Post by walleye »

Cassandra, you are too awesome!
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daal
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Re: Visualizing Tsumego

Post by daal »

walleye wrote:
I am more fascinated with problems that have really simple solutions that are really hard to see.

Here's another problem from a Japanese collection
Click Here To Show Diagram Code
[go]$$B Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . O . . . X X O O . |
$$ | . . . . . . . . . O . X X X O O X X . |
$$ | . . . . . . . O . O X b c d O X O z . |
$$ | . . . . . . . . . X O O a O O X . O . |
$$ | . . . . . . . . O y X O X O X . X . . |
$$ | . . . . . . . . . X X O O X X . . . . |
$$ | . . . . . . . . . . . X X . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]


When I look at it now, the solution is so obvious and so simple, I can't believe I couldn't see it when I first came across it.

A dan level player should be able to solve this in seconds, but I suspect many kyu players will struggle with it for a long time.

I'd really like to know what it is that prevents us from seeing the right moves.


Well after looking at the problem for 2 minutes, I believe that I know part of the reason why I haven't yet solved it. I am seeing a logical problem that goes like this: If I don't keep white in atari until he's dead, he can escape with at least part of his group at y or z. Since no moves from a-d that I can see serve to do this, the problem can't be solved. This is not my last word, but simply a presentation of the way I'm looking at the problem. (Presumably the wrong way).

There must be a flaw in my reasoning, and I suspect it involve z but I can't find it. My guess is that logic is a poor advisor, and that instead I should be looking somewhere that I'm not...
Patience, grasshopper.
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quantumf
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Re: Visualizing Tsumego

Post by quantumf »

walleye wrote:Cassandra, you are too awesome!


Thanks, Cassandra, nice post. As you said, move 1 was obvious, but the thinking for move 3 and 5 utterly eluded me.
btw, I think the term you mean is oi-otoshi (connect and die), not ishi-no-shita (under the stones)
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Re: Visualizing Tsumego

Post by xed_over »

I don't think I overlooked any of the points you mentioned "might be overlooked", but I did overlook this one
Cassandra wrote:
Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ . . . . . . . . . . . . |
$$ . . . O . . . X X O O . |
$$ . . O . X X X O O X X . |
$$ O . O X 3 O 5 O X O . . |
$$ . . X O O a O O X . O . |
$$ . O 4 X O . O X . X . . |
$$ . . X X O O X X . . . . |
$$ . . . . X X . . . . . . |
$$ . . . . . . . . . . . . |[/go]

Black continues with 3. White cannot play at a, because this would mean taking an own liberty. After Black gives Atari with 5, the position is symmetrical again.


I totally overlooked the shortage of liberties issue as to why 4 couldn't be played at 5 or a, and in addition, the symmetry of 3 at 3 or 5 just caused my brain to overload.

plus, I was probably trying to ...
kill both white groups, instead of just one
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Cassandra
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Re: Visualizing Tsumego

Post by Cassandra »

quantumf wrote:btw, I think the term you mean is oi-otoshi (connect and die), not ishi-no-shita (under the stones)

No, I indeed meant Ishi-no-shita.

I think that the position after White 2 - which is after capturing two Black stones - given as primary problem would be easier to solve.
The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)
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Re: Visualizing Tsumego

Post by hyperpape »

Daal, if you have yet to look, think about your premises. Sometimes you can't see how they could be false, but they are.
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Re: Visualizing Tsumego

Post by Fedya »

walleye wrote:I sometimes come across a problem that looks simple enough, but I end up staring at it for a long time before I finally get it.

Here's one of them. Note the time, open the hidden and once you've solved it tell me how long it took you.

Click Here To Show Diagram Code
[go]$$B Black to play
$$ , . . . . . , . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . O . O . . |
$$ . . . . . . O . . . |
$$ , . . . O O X O . . |
$$ . . . . O X X X X X |
$$ . . . . . O O X . . |
$$ . . . . . . . . O . |
$$ --------------------[/go]


10 minutes (KGS 6k), and I still have no idea if I've got the right answer.

Click Here To Show Diagram Code
[go]$$B B1, with the threat of playing at a.
$$ , . . . . . , . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . O . O . . |
$$ . . . . . . O . a . |
$$ , . . . O O X O . . |
$$ . . . . O X X X X X |
$$ . . . . . O O X . . |
$$ . . . . . . 1 . O . |
$$ --------------------[/go]


Off to read the stronger posters' solutions and see if I got this right.
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quantumf
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Re: Visualizing Tsumego

Post by quantumf »

Cassandra wrote:
quantumf wrote:btw, I think the term you mean is oi-otoshi (connect and die), not ishi-no-shita (under the stones)


No, I indeed meant Ishi-no-shita.


Every time I thought about replying to this, I think of this: http://xkcd.com/386/
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Re: Visualizing Tsumego

Post by Joaz Banbeck »

daal wrote:
walleye wrote:
I am more fascinated with problems that have really simple solutions that are really hard to see.

Here's another problem from a Japanese collection
Click Here To Show Diagram Code
[go]$$B Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . O . . . X X O O . |
$$ | . . . . . . . . . O . X X X O O X X . |
$$ | . . . . . . . O . O X b c d O X O z . |
$$ | . . . . . . . . . X O O a O O X . O . |
$$ | . . . . . . . . O y X O X O X . X . . |
$$ | . . . . . . . . . X X O O X X . . . . |
$$ | . . . . . . . . . . . X X . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]


When I look at it now, the solution is so obvious and so simple, I can't believe I couldn't see it when I first came across it.

A dan level player should be able to solve this in seconds, but I suspect many kyu players will struggle with it for a long time.

I'd really like to know what it is that prevents us from seeing the right moves.


Well after looking at the problem for 2 minutes, I believe that I know part of the reason why I haven't yet solved it. I am seeing a logical problem that goes like this: If I don't keep white in atari until he's dead, he can escape with at least part of his group at y or z. Since no moves from a-d that I can see serve to do this, the problem can't be solved. This is not my last word, but simply a presentation of the way I'm looking at the problem. (Presumably the wrong way).

There must be a flaw in my reasoning, and I suspect it involve z but I can't find it. My guess is that logic is a poor advisor, and that instead I should be looking somewhere that I'm not...


The think the oversight is in the definition of the problem. By saying: "...he can escape with at least part of his group...", you seem to imply that allowing white to do so would be a failure. But what exactly is the definition of the problem? Is it to kill all the white stones? Is it to rescue the black stones at the top?

All that was presented to us was:
walleye wrote:...
Here's another problem from a Japanese collection...

What exactly is the goal of the problem?
Help make L19 more organized. Make an index: https://lifein19x19.com/viewtopic.php?f=14&t=5207
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